Biblioteca Nacional de Portugal , Portugal's national library in Lisbon. During the Middle Ages, the monastery quickly became a powerful and influential presence within the kingdom of Portugal. The monastery owned and developed extensive agriculture areas, and the abbot exerted influence over a large area. A public school was opened in 1269. The importance of the monastery can be measured by the fact that many monarchs were buried here in the 13th and 14th centuries. Kings Afonso II and Afonso III and their queens Urraca of Castile and Beatrice of Castile are buried here, as well as King Pedro I and his mistress, Inês de Castro, who was murdered on the orders of Pedro's father, King Afonso IV. After being crowned king, Pedro commissioned two magnificent Gothic tombs for himself and his mistress, both of which can still be seen inside the monastery church. During the reign of Manuel I, a second floor was added to the cloister and a new sacristy was built, following the characteristic Portuguese late Gothic style known as "Manueline". The monastery was further enlarged in the 18th century, with the addition of a new cloister and towers to the church, although the mediaeval structure was mostly preserved. In the Baroque period, the monks were famous for their clay sculptures, many of them are still inside the monastery. Elaborate tiles and altarpieces completed the decoration of the church. The great 1755 Lisbon earthquake did not cause significant damage to the monastery, although part of the sacristy and some smaller buildings were destroyed. Far greater damage was caused by invading French troops in the first years of the 19th century during the Peninsular War, itself a part of the Napoleonic Wars. In addition to looting the library, they robbed the tombs and stole and burnt part of the inner decoration of the church. In 1834, with the dissolution of the monasteries in Portugal, the last monks left the monastery. Alcobasa Monastery was classified as a National Monument January 1, 1907 and included to the special protection zone on August 16, 1957. Art and architecture The Alcobasa Monastery was built following an early Gothic style, and represents the arrival of this style in Portugal. The church and other main buildings were constructed from 1178 until the end of the 13th century. The church was consecrated in 1252. Following the precepts of the Cistercian Order, the original monastic buildings